If you're looking to dirty bulk like crazy, you can do what I did to gain ~20lbs or so in about two months. Eat like normal, such as 3-6 meals per day depending on size. Base your meals around protein, make sure you eat a lot of meat and a lot of carbs. And then add a gallon of whole milk per day. You'll feel bloated like crazy for the first few days, but after that you'll see quick size and strength gains. You'll lose your abs mostly, but they'll come back after you stop drinking all the milk. Do this for 4-8 weeks, it's up to you. I did it for 8, and gained about 20 pounds and a good amount of strength. Once you're off, you'll lose a few pounds of fat in the next week or so- you'll probably keep at least 90 percent of the weight you gained. Just my experiences. Everyone's different.